Profiling of donor-specific immune effector signatures in response to rituximab in a human whole blood loop assay using blood from CLL patients

M Eltahir,E Fletcher,L Dynesius,J.L Jarblad,M Lord,I Laurén,M Zekarias,X Yu,M.S Cragg,C Hammarström,K.H Levedahl,M Höglund,G Ullenhag,M Mattsson,S.M Mangsbo

doi:10.1016/j.intimp.2020.107226

Abstract

Rituximab is widely used in the treatment of haematological malignancies, including chronic lymphocytic leukaemia (CLL), the most common leukaemia in adults. However, some patients, especially those with high tumour burden, develop cytokine release syndrome (CRS). It is likely that more patients will develop therapy-linked CRS in the future due to the implementation of other immunotherapies, such as CAR T-cell, for many malignancies. Current methods for CRS risk assessment are limited, hence there is a need to develop new methods. To better recapitulate an in vivo setting, we implemented a unique human whole blood “loop” system to study patient-specific immune responses to rituximab in blood derived from CLL patients. Upon rituximab infusion, both complement-dependent cytotoxicity (CDC) and antibody-dependent cellular cytotoxicity (ADCC) profiles were evident in CLL patient blood, coincident with CLL cell depletion. Whereas B cell depletion is induced in healthy persons in the blood loop, only patients display B cell depletion coupled with CRS. With the exception of one donor who lacked NK cells, all other five patients displayed variable B cell depletion along with CRS profile. Additionally, inhibition of CDC or ADCC via either inhibitors or antibody Fc modification resulted in skewing of the immune killing mechanism consistent with published literature. Herein we have shown that the human whole blood loop model can be applied using blood from a specific indication to build a disease-specific CRS and immune activation profiling ex vivo system. Other therapeutic antibodies used for other indications may benefit from antibody characterization in a similar setting.

Highlights

Rituximab is a cornerstone therapy for many B-cell-malignancies, such as follicular lymphoma, diffuse large B cell lymphoma and chronic lymphocytic leukaemia (CLL), either as a monotherapy or in combina tion with chemotherapy [1]
Rituximab induces a drop in white blood cell count and cytokine release in blood from CLL patients but not in blood from healthy donors
In order to investigate if a high white blood cell (WBC) count, i.e. high target cell number, is required for rituximab to induce cytokine release in the blood loop system, we compared responses in blood from six CLL patients with high white blood cell count (WBC) counts to blood from five age-matched healthy donors with normal WBC counts

Summary

Introduction

Rituximab is a cornerstone therapy for many B-cell-malignancies, such as follicular lymphoma, diffuse large B cell lymphoma and chronic lymphocytic leukaemia (CLL), either as a monotherapy or in combina tion with chemotherapy [1]. Rituximab is generally well tolerated, some patients develop infusion reactions manifesting as cytokine release syndrome (CRS) commonly of grade 1–2. This type of reaction has been reported to occur early during rit uximab treatment and has mainly been associated with the first infusion [4]. In CLL patients, high tumour burden is associated with an increased risk of CRS [4]. When CRS occurs, the patient can experience milder symptoms such as fever, nausea and vomiting. In severe cases, involving dyspnoea and hypotension (grade 3–4), CRS can be lifethreatening [5]. A rise in biochemical markers such as TNF-α and IL-6 may be observed [6]

Methods

Results

Conclusion